As cities figure out how to deal with growing piles of trash, they're taking two paths. Some, like San Francisco, are aiming for zero waste—composting and recycling everything that might have otherwise gone to a landfill. Others are burning garbage to turn it into electricity.
In 2020, the same year that San Francisco hopes to become a zero-waste city, the Chinese megacity of Shenzhen will open the world's largest waste-to-energy plant, stretching nearly a mile across and burning 5,000 tonnes of trash every day.
The new incinerator is one of 300 waste-to-energy plants that the Chinese government plans to build over the next three years to help offset the country's rapidly expanding dumps. What makes this plant different—besides its massive size, and sleek design—is the fact that it doubles as a visitor center. A public path winds around the circular plant, explaining each step of the incineration process, before ending up on the solar panel-topped roof.
"The waste challenge is all about education—and experiencing the scale of the challenge is part of that education process," says Chris Hardie, partner at Schmidt Hammer Lassen Architects, which won a competition, along with Gottlieb Paludan Architects, for the design of the new plant.
"Think of it like smoking in the 1950s and 1960s—everyone smoked," he says. "It was only until a civilization became educated on how much it was polluting our own bodies did we dramatically stop. Waste is similar. If you don’t realize the damage it is doing, why stop creating waste?"
In China, most waste currently goes to landfills or illegal dumps—piles of trash so huge that they can actually be dangerous, like the landfill in Shenzhen that collapsed in December and killed dozens of people nearby. It's a space problem, but also a climate problem, because landfills emit potent greenhouse gases as garbage rots away.
Incinerating trash also pollutes, but a state-of-the-art plant like the one planned for Shenzhen can dramatically reduce pollution compared to a city dump. "Burning waste naturally creates pollutants, mainly carbon dioxide—something in the region of one metric ton of CO2 per metric ton of waste," says Hardie. "This does not sound great for sure, but when you compare it to putting the waste to landfill, one metric ton of waste will ultimately produce somewhere in the region of 60 cubic meters of methane as it decomposes—and this has more than twice the negative effect on global warming."
As the plants runs, it can generate some electricity for the city, though incineration is not a major source of energy (and the plant itself runs on solar power, thanks to 44,000 square meters of solar panels on the roof). How much energy it creates will depend on the kind of trash inside—something that will change over time. The better trash is sorted and recycled before anything's sent to the plant, the more efficiently the plant can run. Ultimately, the city will still need to reduce garbage.
"Waste-to-energy plants are not an energy solution," says Hardie. "They are a way of dealing with waste and using this process to generate electricity as a byproduct of the process. Cities have to move towards more recycling and reducing their waste for sure—and of course developing more sources of renewable energy. That is sort of the point we are making by proposing this be the first waste-to-energy plant that has a renewable component to it."
All images courtesy of Schmidt Hammer Lassen